Datasheet

Section 19 Clock Pulse Generator
Rev.7.00 Dec. 24, 2008 Page 606 of 698
REJ09B0074-0700
This LSI
Ouptut port
External
interrupt
EXTAL
Request switchover of external clock
Interrupted external signal
External clock switchover signal
External clock 1
External clock 2
Control
cycle
Selector
Figure 19.11 Example of External Clock Switching Circuit
200 ns or more
(2)
(1)
(2)
(3)
(4)
(5)
Port setting (clock switchover)
Software standby mode transition
External clock switchover
External interrupt generation
(Input interrupt at least 200 ns after transition to software standby mode.)
Interrupt exception handling
(5)
SLEEP instruction
execution
Interrupt exception handling
Operation
External
clock 1
External
clock 2
(1)
Port setting
(3)
External clock
switchover
signal
EXTAL
Internal
clock φ
(4)
Wait time
External
interrupt
Active (external clock 2) Software standby mode Active (external clock 1)
Clock switchover
request
Figure 19.12 Example of External Clock Switchover Timing